Best Procedure for Firming Neck and Chin?

It appears from your question that you don't have a lot of sagging of the neck structures (hanging skin, muscle bands, or fat).  If that is true, then the aging changes that you are seeing are most likely the result of diminished elasticity of the skin, which can cause the skin to crepe and wrinkle, giving the skin a 'chicken'  type of appearance. Loss of bone and fat along the jawline and in the chin itself can also contribute to a tired looking neck. 

When there is significant sagging of the neck structures, surgery is almost always the preferred procedure. But in your case it appears that you might benefit from a combination of less invasive procedures. I begin by assessing the need for filler in the chin and along the jawline. Then I look for ways to improve the tone and quality of the skin. I have had good success tightening and improving the skin of the neck and jawline by using a combination of needle-based radiofrequency and fractional ablative laser resurfacing. We do these procedures simultaneously to restore elastin, collagen and hyaluronic acid in the skin while we also improve the surface texture and visible signs of sun-damage. The procedure can be done safely and the results are very satisfying. 

It’s wonderful that your facial skin is in great condition! For addressing laxity and firmness in the neck and chin area, there are several non-surgical options to consider. Treatments like Facetite use ultrasound technology to stimulate collagen production, tightening the skin over time. Neuromodulators can help reduce horizontal neck lines, while dermal fillers or biostimulators like Sculptra® can restore volume and support the skin's structure. For those with excess fat under the chin, treatments like Belkyra® (Kybella®) can effectively contour the area. A consultation with an experienced provider will help determine the best approach tailored to your goals.

Good question!
It is a bit hard to tell without photos, as people use the term "firming" for many different things. A facelift is the most powerful tool for most of the issues of the lower neck/chin as it will treat sagging soft tissue and excess skin while sometimes also rejuvenating the appearance of the skin itself, but I completely understand not everyone is ready for or needs a facelift. There are other non-surgical options which can improve the quality of this area. If the issue is changes to the skin from sun damage or fine lines, you could benefit from a chemical peel or laser resurfacing. If the issue is excess skin, there are some in office procedures such as radiofrequency and submental liposuction which may be options.
Hope this helps!